Saitama is the bald hero of One Punch Man, a series created by ONE that became a webcomic, manga and anime known for parodying superhero battles. His strength lets him defeat enemies with a single punch, which leaves him bored and emotionally flat in everyday scenes. That attitude turned short lines like his plain ok into a reaction clip shared in edits, chats and streams. It survives because the delivery works even without context, signaling total indifference in under a second.